Movable carriage for a lithographic apparatus and device manufacturing method

ABSTRACT

A movable carriage for moving an article support member in a lithographic apparatus is provided. The article support member is constructed and arranged to move and support an article to be placed in a beam path of the lithographic apparatus. The carriage includes a compartmented composite structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/860,654, filed on Jun. 4, 2004, now U.S. Pat. No. 7,012,264, whichissued on Mar. 14, 2006, the entire content of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a movable carriage for moving anarticle support member in a lithographic apparatus, a method ofmanufacturing a movable carriage, and a device manufacturing method.

2. Description of Related Art

A lithographic apparatus is a machine that applies a desired patternonto a target portion of a substrate. Lithographic apparatus can beused, for example, in the manufacture of integrated circuits (ICs). Inthat circumstance, a patterning device, such as a mask, may be used togenerate a circuit pattern corresponding to an individual layer of theIC, and this pattern can be imaged onto a target portion (e.g. includingpart of, one or several dies) on a substrate (e.g. a silicon wafer) thathas a layer of radiation-sensitive material (resist). In general, asingle substrate will contain a network of adjacent target portions thatare successively exposed. Known lithographic apparatus include so-calledsteppers, in which each target portion is irradiated by exposing anentire pattern onto the target portion in one go, and so-calledscanners, in which each target portion is irradiated by scanning thepattern through the projection beam in a given direction (the“scanning”-direction) while synchronously scanning the substrateparallel or anti parallel to this direction.

In conventional structures for moving and supporting the article supportmember, in particular, a wafer table for supporting a wafer to beirradiated by a radiation beam of the lithographic apparatus, or, a masktable for supporting a mask defining a circuit pattern, due to theextreme accurate positioning requirements, a carriage structure is usedwherein the mechanical stiffness properties are optimal. Furthermore,due to the heat generated by the actuators for moving the carriage, andradiation received on the structure to be irradiated, a substantial needexists to provide cooling in the carriage structure. To this end,conventional materials like aluminum and titanium are used which arecooled by cooling circuits integrated in the structure. One problemrelated to the cooling and stiffness requirements of the carriage isthat the options to provide further reduction of the weight thereof arerather limited, since there are minimum thicknesses to be observed forthe carriage in order to maintain sufficient mechanical integrity. Suchcooling is essential for these conventional materials, since slighttemperature variations can result in unacceptable contracting orexpanding of the material. Even a temperature fluctuation as little as2° K. can cause sensors that are arranged for driving actuators foractuating the carriage to be displaced over a distance to be out oftolerance for placing the substrate on a predetermined position.

BRIEF SUMMARY OF THE INVENTION

It is an aspect of the present invention to overcome the above indicatedproblems and provide a lithographic that includes an illumination systemfor providing a projection beam of radiation; an article support memberfor supporting an article to be placed in a beam path of the projectionbeam of radiation on the article support; and a carriage for alithographic apparatus that is light, stiff, and adequate in terms ofcooling and mounting properties.

In another aspect of the invention, there is provided a movable carriagefor use in a lithographic apparatus. The movable carriage is providedfor moving an article support member in the lithographic apparatus. Thearticle support member is constructed and arranged to move and supportan article to be placed in a beam path of the lithographic apparatus.The carriage includes a compartmented composite structure.

In still another aspect of the invention, there is provided a method formanufacturing a movable carriage for moving an article support member ina lithographic apparatus. The article support member is constructed andarranged to move and support an article to be placed in a beam path ofthe lithographic apparatus. The method includes forming the carriagefrom a compartmented composite structure, and providing thecompartmented composite structure with a non-composite mountinginterface and/or cooling interface.

In a further aspect of the invention, a method for manufacturing adevice with a lithographic apparatus is provided. The method includesprojecting a beam of radiation, supporting an article with an articlesupport member so that the article can be placed in a beam path of thebeam of radiation, and moving the article support member with a carriagethat includes a compartmented composite structure.

In particular, according to the invention, a carriage is provided. Thecarriage includes a compartmented composite structure. With such anarrangement, conventional interfacing, for example, using metal orceramic materials, can be applied in combination with the advantages ofcomposite structures, such as a low specific weight, a high Young'smodulus at places and directions where required, high strength, highstability, high electrical resistivity, and a low coefficient thermalexpansion (CTE). Due to the low CTE value, there is no need for applyinga separate cooling arrangement for the carriage, which means that thecarriage is made lighter and simpler in construction. Furthermore,unlike the conventional materials, like aluminum and titanium, nomagnetic damping occurs, which, where a long stroke actuator in the formof a magnetic motor is used, is highly beneficial.

Furthermore, this particular arrangement offers a low cost product sinceit can be manufactured by gluing together very simple shaped structures.In addition, composite materials offer a range of complex shapes thatare not possible to manufacture by conventional metals and ceramics.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying schematic drawings in whichcorresponding reference symbols indicate corresponding parts, and inwhich:

FIG. 1 depicts a lithographic apparatus according to an embodiment ofthe invention;

FIG. 2 depicts a schematic plan view of a boxed composite structure (a)provided with non-composite interfaces (b) according to the invention.

FIG. 3 shows a perspective view of a plurality of molds for the boxedcomposite structure of FIG. 2 a;

FIG. 4 schematically shows an assembly method for providing a carriageaccording to the invention;

FIG. 5 is a top view of an embodiment of a carriage according to theinvention;

FIG. 6 is a cross-sectional view taken along line A—A of FIG. 5;

FIG. 7 is a cross-sectional view taken along line B—B of FIG. 5;

FIG. 8 an alternative cross-sectional view taken along line B—B of FIG.5;

FIG. 9 is a schematic view of a boxing and ribbing structure forproviding the carriage according to an embodiment of the invention;

FIG. 10 is a schematic view of the boxing and ribbing structure forproviding the carriage according to another embodiment of the invention;

FIG. 11 is a schematic view of the boxing and ribbing structure forproviding the carriage according to another the invention;

FIG. 12 is a schematic view of a mold for use in assembling the carriageaccording to the invention;

FIG. 13 is a schematic view of another mold for use in assembling thecarriage according to the invention; and

FIG. 14 shows a movable carriage for moving an article support memberaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Although specific reference may be made in this text to the use oflithographic apparatus in the manufacture of ICs, it should beunderstood that the lithographic apparatus described herein may haveother applications, such as the manufacture of integrated opticalsystems, guidance and detection patterns for magnetic domain memories,liquid-crystal displays (LCDs), thin film magnetic heads, etc. Theskilled artisan will appreciate that, in the context of such alternativeapplications, any use of the terms “wafer” or “die” herein may beconsidered as synonymous with the more general terms “substrate” or“target portion”, respectively. The substrate referred to herein may beprocessed before or after exposure in, for example, a track (a tool thattypically applies a layer of resist to a substrate and develops theexposed resist) or a metrology or inspection tool. Where applicable, thedisclosure herein may be applied to such and other substrate processingtools. Further, the substrate may be processed more than once, forexample in order to create a multi-layer IC, so that the term substrateused herein may also refer to a substrate that already contains multipleprocessed layers.

The terms “radiation” and “beam” used herein encompass all types ofelectromagnetic radiation, including ultraviolet (UV) radiation (e.g.having a wavelength of 365, 248, 193, 157 or 126 nm) and extremeultra-violet (EUV) radiation (e.g. having a wavelength in the range of5–20 nm), as well as particle beams, such as ion beams or electronbeams.

The term “patterning device” used herein should be broadly interpretedas referring to a device that can be used to impart a projection beamwith a pattern in its cross-section such as to create a pattern in atarget portion of the substrate. It should be noted that the patternimparted to the projection beam may not exactly correspond to thedesired pattern in the target portion of the substrate. Generally, thepattern imparted to the projection beam will correspond to a particularfunctional layer in a device being created in the target portion, suchas an integrated circuit.

The patterning device may be transmissive or reflective. Examples ofpatterning devices include masks, programmable mirror arrays, andprogrammable LCD panels. Masks are well known in lithography, andinclude mask types such as binary, alternating phase-shift, andattenuated phase-shift, as well as various hybrid mask types. An exampleof a programmable mirror array employs a matrix arrangement of smallmirrors, each of which can be individually tilted so as to reflect anincoming radiation beam in different directions; in this manner, thereflected beam is patterned. In each example of patterning device, thesupport structure may be a frame or table, for example, which may befixed or movable as required and which may ensure that the patterningdevice is at a desired position, for example, with respect to theprojection system. Any use of the terms “reticle” or “mask” herein maybe considered synonymous with the more general term “patterning device”.

The term “projection system” used herein should be broadly interpretedas encompassing various types of projection system, including refractiveoptical systems, reflective optical systems, and catadioptric opticalsystems, as appropriate for example for the exposure radiation beingused, or for other factors such as the use of an immersion fluid or theuse of a vacuum. Any use of the term “lens” herein may be considered assynonymous with the more general term “projection system”.

The illumination system may also encompass various types of opticalcomponents, including refractive, reflective, and catadioptric opticalcomponents for directing, shaping, or controlling the projection beam ofradiation, and such components may also be referred to below,collectively or singularly, as a “lens”.

The lithographic apparatus may be of a type having two (dual stage) ormore substrate tables (and/or two or more mask tables). In such“multiple stage” machines the additional tables may be used in parallel,or preparatory steps may be carried out on one or more tables while oneor more other tables are being used for exposure.

The lithographic apparatus may also be of a type wherein the substrateis immersed in a liquid having a relatively high refractive index, e.g.water, so as to fill a space between the final element of the projectionsystem and the substrate. Immersion liquids may also be applied to otherspaces in the lithographic apparatus, for example, between the mask andthe first element of the projection system. Immersion techniques arewell known in the art for increasing the numerical aperture ofprojection systems.

FIG. 1 schematically depicts a lithographic apparatus according to aparticular embodiment of the invention. The apparatus includes: anillumination system (illuminator) IL for providing a projection beam PBof radiation (e.g. UV or EUV radiation); a first support structure (e.g.a mask table) MT for supporting a patterning device (e.g. a mask) MA andconnected to a first positioning device PM for accurately positioningthe patterning device with respect to item PL; a substrate table (e.g. awafer table) WT for holding a substrate (e.g. a resist coated wafer) Wand connected to a second positioning device PW for accuratelypositioning the substrate with respect to item PL; and a projectionsystem (e.g. a reflective projection lens) PL for imaging a patternimparted to the projection beam PB by the patterning device MA onto atarget portion C (e.g. including one or more dies) of the substrate W.

As here depicted, the apparatus is of a reflective type (e.g. employinga reflective mask or a programmable mirror array of a type as referredto above). Alternatively, the apparatus may be of a transmissive type(e.g. employing a transmissive mask).

The illuminator IL receives a beam of radiation from a radiation sourceSO. The source and the lithographic apparatus may be separate entities,for example, when the source is a plasma discharge source. In suchcases, the source is not considered to form part of the lithographicapparatus and the radiation beam is generally passed from the source SOto the illuminator IL with the aid of a radiation collector includingfor example suitable collecting mirrors and/or a spectral purity filter.In other cases, the source may be integral part of the apparatus, forexample, when the source is a mercury lamp. The source SO and theilluminator IL, may be referred to as a radiation system.

The illuminator IL may include an adjusting device for adjusting theangular intensity distribution of the beam. Generally, at least theouter and/or inner radial extent (commonly referred to as σ-outer andσ-inner, respectively) of the intensity distribution in a pupil plane ofthe illuminator can be adjusted. The illuminator provides a conditionedbeam of radiation, referred to as the projection beam PB, having adesired uniformity and intensity distribution in its cross section.

The projection beam PB is incident on the mask MA, which is held on themask table MT. Being reflected by the mask MA, the projection beam PBpasses through the lens PL, which focuses the beam onto a target portionC of the substrate W. With the aid of the second positioning device PWand position sensor IF2 (e.g. an interferometric device), the substratetable WT can be moved accurately, e.g. so as to position differenttarget portions C in the path of the beam PB. Similarly, the firstpositioning device PM and position sensor IF1 can be used to accuratelyposition the mask MA with respect to the path of the beam PB, e.g. aftermechanical retrieval from a mask library, or during a scan. In general,movement of the object tables MT and WT will be realized with the aid ofa long-stroke module (coarse positioning) and a short-stroke module(fine positioning), which form part of the positioning devices PM andPW.

Another part of the positioning device PM and/or PW is a carriage whichfurther embodies the invention and which will be further explained withreference to FIG. 2. Generally, this carriage may be seen as a stiffstructure that moves over a perfectly flat surface, moved by the longstroke module. Generally, such a long stroke module may be provided bylinear magnetic motors, which are mounted in transverse directions forcovering a two-dimensional range of positions. However, preferably, thelong stroke module includes a planar electro magnetic motor of the typethat is for instance described in European patent EP-A-1243972, thecontents of which are herein incorporated by reference. On top of thecarriage, generally, the short stroke module is mounted for providing afine positioning of the wafer table, which is mounted on top of theshort stroke module. Thus, the carriage provides a frame between thelong and short stroke modules and as such must be light weight and mustprovide high stiffness in combination with heavy loads.

However, in the case of a stepper (as opposed to a scanner) the masktable MT may be connected to a short stroke actuator only, or may befixed. Mask MA and substrate W may be aligned using mask alignment marksM1, M2 and substrate alignment marks P1, P2.

The depicted apparatus can be used in the following preferred modes:

1. In step mode, the mask table MT and the substrate table WT are keptessentially stationary, while an entire pattern imparted to theprojection beam is projected onto a target portion C in one go (i.e. asingle static exposure). The substrate table WT is then shifted in the Xand/or Y direction so that a different target portion C can be exposed.In step mode, the maximum size of the exposure field limits the size ofthe target portion C imaged in a single static exposure.

2. In scan mode, the mask table MT and the substrate table WT arescanned synchronously while a pattern imparted to the projection beam isprojected onto a target portion C (i.e. a single dynamic exposure). Thevelocity and direction of the substrate table WT relative to the masktable MT is determined by the (de-)magnification and image reversalcharacteristics of the projection system PL. In scan mode, the maximumsize of the exposure field limits the width (in the non-scanningdirection) of the target portion in a single dynamic exposure, whereasthe length of the scanning motion determines the height (in the scanningdirection) of the target portion.

3. In another mode, the mask table MT is kept essentially stationaryholding a programmable patterning device, and the substrate table WT ismoved or scanned while a pattern imparted to the projection beam isprojected onto a target portion C. In this mode, generally a pulsedradiation source is employed and the programmable patterning device isupdated as required after each movement of the substrate table WT or inbetween successive radiation pulses during a scan. This mode ofoperation can be readily applied to maskless lithography that utilizesprogrammable patterning device, such as a programmable mirror array of atype as referred to above.

Combinations and/or variations on the above described modes of use orentirely different modes of use may also be employed.

Turning to FIGS. 2 a and 2 b, there is illustrated a top view of acompartmented composite structure 1. The composite structure 1 ismanufactured of fiber enforced composite materials, such as carbonfibers, etc., and assembled as further indicated with reference to FIG.4. A characteristic feature of the shown exemplary embodiment is arectangular outer box 2 and a triangular inner box 3 provided in theouter box 2. Such an arrangement provides a very stiff structure, whilestill providing access to the interior of the compartmented structurewhich is used for housing wiring and electronics etc. (not shown). Thetriangular inner box 3 may be further divided by sub boxes and ribbingstructures such as illustrated in FIG. 4 and FIGS. 9–11 in particular. Astructure providing optimum access to the interior of the carriage isprovided, while cooling ducts 4 are provided and arranged along the ribsof the structure, such as is illustrated in FIG. 2 b. Here, thecomposite structure 1 of FIG. 2 a is shown provided with a non-compositemounting interface 5 arranged near the corners of the triangle 3, formounting a short stroke motor (not shown). Furthermore, the cooling duct4, which is preferably constructed from aluminum, titanium, or stainlesssteel material or the like, provides cooling to the short stroke motor.The duct 4 may partly be formed by the composite box structure, forinstance, by using an elongate compartment as a cooling duct. For suchan embodiment, the metal surface may be only present at the coolinginterface, which provides coolant to relevant electronic parts such asthe short-stroke actuator (not shown), which may further minimizeweight. The coolant ducts 4 are provided as a triangular metal plate 6that covers the top face of the boxed structure 1, and corners of theplate are used for mounting the short-stroke module, thereby providingan optimum mounting arrangement for ultra stable positioning of thewafer table. Furthermore, robust corner elements 7 are added, generallyof a metal material, for providing a high load interface providingimproved stiffness and protection when the carriage structure 1unexpectedly crashes against a side wall of the surface on top of whichit is actuated.

FIG. 3 clearly shows that the complex composite structure of theinvention may be provided by assembly of substantially simple shapedstructures such as square or triangular shapes that are easy tomanufacture using molds 8, as also indicated with reference to the FIGS.12 and 13. By using these molds 8, more complex shapes can be realizedand integrated in order to reduce the amount of parts (production steps)that have to be glued together afterwards. As shown in FIG. 4, a seriesof assembly steps using these molds 8 is depicted, starting from theright bottom picture and adding subsequently a first upstanding rimcontour 10 on a bottom plate 9. Next, a square upstanding rectangularcontour 11 is provided, which is mounted on the bottom plate 9. Atriangular shaped box 12 is inserted in the rectangular contour 11, thetriangular box provided with an L-form extremal mounting profile forgluing to a top plate 13. Next, further box elements 14 for providinggreater stiffness to the carriage may be added. Finally top plate 13 ismounted and glued on top of the upstanding contours 11, 12 and 14.

FIG. 5 shows a top view of the triangular structure 11, furtherelucidated with reference to FIG. 6-8 showing a plurality ofcross-sectional views for the composite structure. FIG. 6 shows across-sectional view of the triangular structure 12, at position A—A(FIG. 5). Here, upstanding profile may be a U-formed profile, havingL-form extremal mounting profiles for gluing the structure 12 to abottom plate 9 and/or top plate 13. Between the rectangular outercontour 11 and the triangular inner structure 12, a mounting interfaceof, for example, an aluminum plate 15 may be provided.

FIG. 7 and FIG. 8 show alternatives for the cross sectional areadepicted as B—B in FIG. 5. According to FIG. 7, the outer contours 11and inner contour 12 are provided as boxes, which is also depicted inFIG. 4. Thus, the inner triangular box 12 is glued on base plate 9,having upstanding contours 11 integral with the base plate 9. Top plate13 is mounted on the upstanding contours 11, 12 using L-form extremalmounting profiles 16. FIG. 8 shows an alternative configuration, where acomplex upper member 17 partly forms the rectangular structure 11 (sidechambers 18) and triangular structure 12 (inner chamber). A lower bottomplate 19 forming a bottom plate for the triangular structure 12 may beglued to the complex member 17.

FIGS. 9–11 show a plurality of alternative boxing and ribbing structuresfor providing the carriage according to the invention. FIG. 9 shows thata complex structure 20 as shown, for example, in FIG. 8 may be furtherprovided with ribbing structures 21 by using a single sheet 22 ofcomposite material. After removing a top section 23 of the complexstructure 20, the ribs 21 stand upright and may be glued to a top sheetafterwards. FIG. 10 shows a variety of ribbing elements 21, inparticular, a narrow asymmetrical rib 24, which only has one side L-formextremal mounting profile 16, a wide rib 25 which forms an interiorchamber 26 and a symmetrical rib 27, which only has both sides L-formextremal mounting profiles 16. These interior chambers 26 could, forexample, be used as cooling ducts, or, such as indicated by FIG. 9, havethe top side 28 milled to provide two asymmetrical ribs. Also, asindicated by FIG. 11, extra boxes 29 may be added to create symmetricalribs.

FIGS. 12–13 provide exemplary embodiments for molds 8 for use inassembling the carriage according to the invention. The molds 8 arewrapped up to provide a single piece 30. By using a single sheet andseveral molds, multiple compartments 31 may be provided. The molds 8 areremoved by milling the top surface of the pieces 30. FIG. 13 may be usedin combination with the interior molds 8, such as depicted in FIG. 12.Depicted is an exterior mold 32 which, by side walls 33 defines thecontour of rectangular box 11, and by interior bulk part 34 defines thetriangular shape of triangular structure 12.

FIG. 14 shows a movable carriage 35 for moving a wafer table 36 in alithographic apparatus for moving and supporting an article 37 to beplaced in a beam path of the lithographic apparatus. The carriage 35includes a compartmented composite structure as indicated with referenceto the FIGS. 2 a and 2 b. As can be seen in the figures, a plurality ofsensors 38, 39 are mounted on the carriage 35, which are used forpositioning the article 37 with respect to a positional reference 40.These sensors are located at a distance D, which, in principle, can beresponsible for position measurement problems due to temperatureeffects. However, due to the very low coefficient of thermal expansion,especially where the used composite materials 41 include carbon fibers,these variations can be kept within a controllable range. Additionalcooling of the carriage frame 35 may thereby be circumvented. Thisresults in a lighter and simpler construction.

A first sensor 38 is for positioning the carriage with respect to thelong stroke actuator, which, for example may be a planar motor 42. Asecond sensor 39, located at a position different from the first sensor38, is for positioning the wafer table 36 with respect to the carriage35, in order to position the article 37. The second sensor 39communicates with the short stroke actuator 43 that is mounted on top ofthe carriage 35. This may be performed by conventional mountinginterfaces 44, optionally included with cooling interfaces, that areglued on the composite material of the carriage 35.

Although the invention has been described with reference to a carriagestructure specifically designed for carrying the short stroke module ofa wafer table, it is not limited thereto, but, in practice, could alsobe used for other interfaces between long- and short stroke actuators.These actuators, for example, could be present in a mask table of aphotolithographic apparatus using reflective mask technology orarrangements for actuating other elements into the light beam such as aobscuring blades or the like.

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. The description is not intended to limit theinvention.

1. A movable carriage for moving an article support member in alithographic apparatus, said article support member constructed andarranged to move and support an article to be placed in a beam path ofsaid lithographic apparatus, said carriage comprising a compartmentedcomposite structure.
 2. A movable carriage according to claim 1, whereinsaid carriage is constructed and arranged to provide an interfacebetween a long stroke and a short stroke actuator in the lithographicapparatus, and wherein said carriage further comprises a first sensorfor driving said long stroke actuator and a second sensor, positioned ata distance from said first sensor, for driving said short strokeactuator so as to arrange said article to be placed on a predeterminedlocation.
 3. A movable carriage according to claim 1, further comprisinga non-composite mounting interface and/or cooling interface for mountingand/or cooling a short stroke actuator.
 4. A movable carriage accordingto claim 3, wherein said carriage is uncooled.
 5. A movable carriageaccording to claim 3, wherein said non-composite mounting interfacecomprises a metal and/or ceramic material glued to said compositematerial.
 6. A movable carriage according to claim 3, wherein saidcooling interface comprises a metal cooling surface.
 7. A movablecarriage according to claim 6, wherein said metal cooling surface iscoupled to a duct for ducting coolant.
 8. A movable carriage accordingto claim 7, wherein said duct comprises a composite material.
 9. Amovable carriage according to claim 1, wherein said composite is chosenfrom a group of low coefficient of thermal expansion (CTE) materials.10. A movable carriage according to claim 9, wherein said compositecomprises carbon fiber.
 11. A movable carriage according to claim 1,wherein said composite structure comprises at least one composite boxstructure.
 12. A movable carriage according to claim 11, wherein saidbox structure comprises a base plate and upstanding contours.
 13. Amovable carriage according to claim 12, wherein the upstanding contoursare integral with the base plate.
 14. A movable carriage according toclaim 12, wherein the upstanding contours comprise an L-form extremalmounting profile for gluing to a cover plate.
 15. A movable carriageaccording to claim 11, wherein said composite box structure comprises arectangular outer box and a triangular inner box provided in said outerbox.
 16. A movable carriage according to claim 11, wherein saidcomposite box structure comprises a composite rib structure.
 17. Amovable carriage according to claim 16, wherein said rib structure isglued to the box structure.
 18. A movable carriage according to claim17, wherein said rib structure comprises an L-form extremal mountingprofile for gluing to a cover plate.
 19. A movable carriage according toclaim 1, wherein said composite structure comprises a plurality of boxedcompartments glued together.